Artificial teeth



March 30, 1937. w o 2,075,556

, ARTIFICIAL TEETH Filed May 24, 1934 11v VENTOR I j A TTORN Y$ PatentedMar. 30, 1937 UNITED STATES PATENT OFFICE- ARTIFICIAL TEETH Merrill G.Swenson, New York, N. Y.

Application May 24, 1934, Serial No. 727,209

4 Claims.

This invention relates to artificial teeth and has for an object toprovide posterior teeth for tact during mating of the upper and lowerjaws is reduced, and the tendency to lateral or longitudinalinterlocking, setting or wedging effects is practically eliminated.

Another object consists in providing said teeth in which the occlusalsurfaces consist substantially of two planes lying at a very obtuseangle to each other, and with the junction of the said planes preferablysubstantially in line with the longitudinal central axis of the jawportion in which they are set.

Another object consists in providing said teeth in which the occlusalsurfaces of the four teeth in line on either side of either jaw have theplane surfaces just described so arranged that the meet- 5 ing angle ofthe planes becomes progressively more obtuse from the rearmost molar tothe forward bicuspid.

Another object consists in providing such teeth in which the occlusalsurfaces are fashioned with depressions or recesses which substantiallyreduce the contact area and, in effect, present ridges on the occlusalsurfaces to aid in the mastication or trituration of food.

Another object consists in providing such teeth in which the occlusalsurfaces, particularly of the molars, are formed with grooves or thelike constituting escapements or vents from the said depressions orrecesses.

A further object consists in providing certain improvements in the form,construction, and arrangement of the teeth whereby the above named andother objects may effectively be attained.

A practical embodiment of the invention is represented in theaccompanying drawing in which;

Fig. 1 represents a detail side elevation of the lower and upperposterior teeth on one side of the jaw, in mating or masticatingrelation.

Fig. 2 represents a section taken in the plane of the line IIII of Fig.1, looking in the direction 50 of the arrows.

Fig. 3 represents a section taken in the plane of the line IIIIII ofFig. 1, looking in the direction of the arrows.

Fig. 4 represents a longitudinal vertical central 55 section through theparts shown in-Fig. 1.

Fig. 5 represents a plan view of the occlusal surfaces of the upperposterior teeth;

Fig. 6 represents a similar view of the lower posterior teeth; and

Fig. '7 represents an enlarged diagrammatic view showing the contactareas of the upper and lower sets of posterior teeth in one position.

The upper teeth may, for convenience, be marked l, 2, 3, 4, startingwith the rearmost molar and the lower teeth be marked 5, 6, I, 8, alsostarting from the rear.

By reference to the several views, it will be observed that the occlusalor contact surfaces of the teeth, instead of being provided with cuspsor individual projections fitted to mate with complementary depressions.inthe surfaces of the opposing teeth, are formed so as substantially toconsist of two planes meeting in substantially the center of the toothat a very obtuse angle, the said line of meeting being depressed belowthe occlusal surfaces at the inner and outer, or lingual and buccal,sides of the tooth. The said plane surfaces of the lower rear molar 5are denoted by 9, l0, and the corresponding surfaces of the upper molarlbyl I, I2. The form just described is well shown in Fig. 2 of thedrawing, and it will be seen that it enables the upper and lower teethto have a ridge and groove contact which facilitates masticatiomwhilethe ridge and groove are so low and shallow as not to permitinterlocking or to lead to objectionable lateral stresses.- Indeed, theangles formed by the plane surfaces 9, ill on the-one hand and H, l2 onthe other, are so obtuse as to enable the upper and lower teeth to slideupon each other slightly, in both longitudinal and lateral directions,so as to greatly ,promote trituration of food.

The meeting angle of the planes forming the occlusal surfaces of theteeth preferably is slightly more obtuse in the teeth marked 2, 6 thanin the teeth marked I, 5; while the said angle in the teeth marked 3, Iis slightly more obtuse than in the teeth marked 2, 6; and the angle inthe teeth marked 4, 8 is still more obtuse. This brings about aformation such that, when the said four teeth are set in a denture, thecombined occlusal surfaces consist of two planes meeting at a depressedangle along the central axis of the jaw member, with the meeting anglebecoming gradually more pronounced or acute toward the rear. Thisformation substantially promotes bi-lateral balance andharmony of jawarticulation and movement while enabling thorough mastication withanelimination or, at least, great reduction of, lateral interference andstresses.

In addition to the slight angular graduation in .the plane surfaces ofthe sets of four teeth, as hereinabove described, the longitudinalengagement of the upper and lower sets is caused to 5 take place on aslightly curved longitudinal plane by so regulating the slope of theocclusal surfaces and the setting and height of the several teeth as toimpart a slightly convex longitudinal surface to the set of four upperteeth, and a corresponding concave longitudinal surface to the set oflower teeth. This is represented in Fig. 4 and is also indicated in Fig.1.

The occlusal surfaces of the teeth are formed with a number ofdepressions or recesses which are denoted by the numbers I3, l4, l5, l6,l1, l8, I9, 20, in the upper set of posterior teeth shown in Fig. 5, andby 2|, 22, 23, 24, 25, 26, 21, 28, 29, 30, in the lower set shown inFig. 6. The exact formation, size, location and arrangement of theseseveral depressions are not matters of prime importance, the intentionbeing to fashion the surfaces into depressions and ridges while stillleaving the occlusal surfaces in the form of the angularly disposedplanes hereinbefore described. In other words, the depressions andridges are not formed so as to act in any respect the same as cuspinterdigitation, but merely to facilitate mastication or triturationaccomplished by the sliding and grinding action of the meeting planesurfaces.

The ridges formed by the depressions or recesses are well shown in Figs.4, 5 and 6. They may be indicated generally by the numerals ii, 32, 33and 34 in respect to the upper teeth shown 35 in Fig. 5; and by thenumerals 35, 38, 31 and 33 in the lower teeth shown in Fig. 6.

It will be observed that the ridges on the set of upper teeth, shown inFig. 5, have a different angular disposition from those on thelower'teeth 40 shown in Fig. 6 so that, when the said sets of teeth arebrought into mating engagement, the ridges cross each other to a certainextent and thereby prevent any interlocking while promotingtrituration-.. This angular disposition of the ridges and theireffective contact areas are diagrammatically shown in Fig. 7 of thedrawing in which the ridges on the lower set of posterior teeth aredenoted by A; the ridges on the upper set of posteriorteeth by B; andthe contact areas.

which. are shaded in the figure, by C.

The ridges, particularly on the molars I, 2, I, 8, are broken away atone or more points, preferably on the lingual and buccal sides, to formescapements or drains for the recesses. These escapements are indicatedby 33, 40, 4|, 42, in the molars shown in Fig. 5; and by 43, 44, 45, 46,41 and 48 in the molars shown in Fig. 6. These escapements assist in themastication of food by way of facilitating the emptying of the recessesand preventing them from becoming clogged with packed food particles soas to tend to reduce the benefit of the recesses by lessening thegrinding and cutting action of the ridges intermediate the recesses.

Reference to the drawing, particularly Figs. 2

and 3, will show that the buccal surfaces of the maxillary or upperteeth, and the lingual surfaces of the mandibular or lower teeth aresubstantially straight or flat, or very slightly curved, as contrastedwith the bulging form of these parts of previous artificial teeth. Thisformation serves not only to improve the general efficiency of theteeth, but it makes the adjacent edges sharper and thereby specificallyenhances to a substantial '75 extent the ease and thoroughness withwhich they penetrate the food that is being masticated. Likewise, thisimprovement tends to reduce the size and weight of the teeth.

Certain features of advantage inherent in the subject matter of thisinvention may be summarized as follows:

The teeth will balance and harmonize with law movement but withoutcuspinterdigitation. They will balance by means of planes instead of bymeans of cusps. They will glide over each other as though there were noopenings or recesses in the plane surfaces although the rea of therecesses is greater than the remaining area of the occlusal surfaces. Inspite of the fact that they work in co-operation as plane surfaces,there is really less porcelain contact than with the cusp form of teeth.'The recesses or depressions which reduce occlusal contact are out ofthe contact line of the planes. The slight but gradual rearwardlyincreasing angle of the plane surfaces serves materially to reducelateral interference while maintaining balance and harmony of jawmovement. The ridges formed by the recesses or depressions are disposedso as to lie in angular relationship in the upper teeth as compared withthe lower teeth, which prevents setting or interlocking of the teeth andalso promotes trituration.

the teeth embedded in the gum or jaw material,

marked 49 and 50, is not intended to be significant or accurate indetail; because the shape of this portion of the teeth and the manner oftheir mounting in the denture constitutes no part of my invention. Anywell known or preferred form and manner may be adopted in thisconnection. It will be understood ,that various changes may be resortedto in the form, construction, arrangement and materials, withoutdeparting from the spirit and scope of my invention; and hence I do notintend to be limited to the details herein shown and described, exceptas they are included in the claims.

What I claim is: 1. In a denture, sets of upper and lower posteriorteeth, each set havlngtheir occlusal contact surfaces formedsubstantially in two planes angularly disposed with respect to eachother and meeting at a point intermediate and below the lingual andbuccal sides of the occlusal surfaces, the meeting angle of said planesgrowing gradually more acute from the front tooth of a set to the reartooth of a set, and said plane surfaces being provided with recessesforming depressions in said surfaces with intermediate ridges, theridges on each set being arranged in angular relationship to the ridgesonthe other set.

2. In a denture, sets of upper and lower posterior teeth, each sethaving their occlusal contact surfaces formed substantially in twoplanes angularly disposed with respect to each other and meeting at apoint intermediate and below the lingual and buccal sides oftheocclusalsurfaces, the meeting angle of said planes "growing gradually more acutefrom the front tooth of a set to the rear tooth of a set, the occlusalsurfaces of one set as a whole being slightly convex in a longitudinaldirection and the occlusal surfaces of the other set being slightlyconcave in a longitudinal direction.

3. In a denture, sets of upper and lower posterior teeth, each sethaving their occlusal contact surfaces formed substantially in twoplanes angularly disposed with respect to each other and meeting at apoint intermediate and below the lingual and buccal sides of theocclusal surfaces, the meeting angle of said planes growing graduallymore acute from the front tooth of a set to the rear tooth of a set, andsaid plane surfaces being provided with recesses forming depressions insaid surfaces with intermediate ridges, the ridges on each set beingarranged in angular relationship to the ridges on the other set, theocclusal surfaces of one set as a whole being slightly convex in alongitudinal direction and the occlusal surfaces of the other set beingslightly concave in a longitudinal direction.

4. In a denture, sets of upper and lower posterior teeth, each sethaving their occlusal contact surfaces formed substantially in twoplanes angularly disposed with respect to each other and meeting at apoint intermediate and below the lingual and buccal sides of theocclusal surfaces, the meeting angle of said planes growing graduallymore acute from the front tooth of a set to the rear tooth of a set, andsaid plane surfaces being provided with recesses forming depressions insaid surfaces with intermediate ridges, the ridges on each set beingarranged in angular relationship to the ridges on the other set, saidrecesses being freely open at a side to provide for escapment andprevent material from lodging therein, the occlusal surfaces of one setas a whole being slightly convex in a longitudinal direction and theocclusal surfaces of the other set being slightly concave in alongitudinal direction.

MERRILL G. SWENSON.

